This invention relates to apparatus and method for the delivery of gaseous fuels to internal combustion engines which use hydrocarbon as a fuel, particularly the engines of automobiles, trucks, tractors and airplanes.
The rapidly rising cost of gasoline during the last few years has encouraged interest in the use of alternative fuels in such engines and one of the alternatives is a class of fuels referred to as gaseous fuels. By gaseous fuels herein is meant hydrocarbon fuels which are gaseous under ambient conditions or light hydrocarbon liquids which become gaseous by preheating. Examples of these fuels are liquefied petroleum gases (LPG) containing propane or butane or mixtures of both, liquefied natural gas (LNG) containing predominantly methane with some ethane but no more than trace quantities of other materials, compressed natural gas (CNG) being more or less the same components as LNG but pressurized and not liquefied, and natural gas liquids (NGL) which are separated as liquids during the production of natural gas and contain, besides butane and propane, some ethane, pentane and heavier fractions. It is understood that reference herein to LPG includes all of the aforementioned gaseous fuels.
As a result of recent discoveries in the North Sea and other areas of the West, there is the prospect of a more plentiful supply of gaseous fuels becoming available over the next 10-20 years at prices below that of the cost of gasoline.
Gaseous fuels, LPG in particular, have been used with internal combustion engines for a long time. However, recent developments in federal mileage and emission requirements for the automotive and trucking industry have made it increasingly difficult to convert existing automobile and truck models to the use of LPG and continue to meet those requirements. This is especially the case for new models and those which will be coming off the assembly lines in the foreseeable future. In order to meet government mandated fleet mileage requirements and limits on emissions, manufacturers have been forced to rely heavily on regulating quite closely the operation of each engine. New vehicles are being produced with electronic ignition systems and computer controls which monitor engine operating parameters and adjust virtually on a continuous basis the air fuel mixture and engine timing.
One consequence of such sophisticated engine controls is the non-compatibility of existing devices which are used to convert an engine from gasoline use to LPG or other gaseous fuel operation. That is, when a conversion is made utilizing equipment heretofore available for supplying the LPG to the engine, conditions are created which are no longer recognizable by the control systems in place, and engine performance in terms of mileage and emissions is damaged if not totally destroyed. In other words, under the technology in existence prior to this invention, conversion from gasoline to LPG would require a major change in the control system supplied by the manufacturer. This would make the conversion either completely infeasible in terms of the economics or at best marginally so, plus there are technical problems which develop having to do with subsequent service and maintenance. In any event, prior to this invention the conversion of gasoline engines to LPG fuel has become more difficult if not completely impossible.